Fundamental principles of crosstalk in optical data storage

Cross talk in the read out signal resulting from narrow track pitches is analyzed with a Babinet decomposition of the light reflected from the disk surface. Results indicate that the commonly used technique of measuring cross talk does not adequately describe the temporal behavior of cross talk effects because the intermodulation of the scan-track mark pattern and the adjacent-track mark pattern is not considered. Our analysis takes this inter-modulation into account and shows its significance. The analysis presents a fundamentally new way to conceptualize cross talk in which effects due to different terms of the Babinet decomposition can be studied separately or combined in meaningful signal groups that relate directly to measurements. Example calculations are presented that illustrate the behavior of the readout signal from optical disks that might be used for land-and-groove recording. Quantification of cross talk effects are presented with respect to shifts of signal transitions.